The present invention relates to catheterization. More particularly it relates to a catheter suitable for guidance and positioning within the patient""s body using the monorail positioning method or similar methods involving the engagement of the distal end of the catheter to a guide-wire and guiding it by advancing the catheter""s distal end along the guide-wire.
Catheterization is a well-known regular procedure, employed as a part of various medical treatments, such as intravascular catheterization, urinary catheterization, endotracheal catheterization, brain catheterization (shunt), and other types of catheterization.
In particular, cardiac pacemaker implant procedure had become a standard procedure in cardiology in the past few decades. Cardiac pacemaker implant procedure generally includes implanting the body of the pacemaker itself and one or two pacing electrode leads, usually inserted in the right chamber or atrium of the heart, and providing electric stimuli to the cardiac muscle through the electrodes.
Excitable tissue control (ETC) devices are devices which modulate the activity of excitable tissues by application of non-excitatory electrical field signals to the excitable tissue through suitable electrodes in contact with the tissue. For example, ETC devices may be used, inter alia, to increase or decrease the contractility of cardiac muscle in vitro, in vivo and in situ., as disclosed in detail in PCT application PCT/IL97/00012 (International Publication Number WO 97/25098) to Ben-Haim et al., titled xe2x80x9cELECTRICAL MUSCLE CONTROLLERxe2x80x9d, incorporated herein by reference. Other methods and applications of ETC devices are disclosed in PCT application PCT/IL97/00231 (International Publication Number WO 98/10828) titled xe2x80x9cAPPARATUS AND METHOD FOR CONTROLLING THE CONTRACTILITY OF MUSCLESxe2x80x9d to Ben Haim et al., incorporated herein by reference, PCT application PCT/IL97/00232 (International Publication Number WO 98/10829) titled xe2x80x9cDRUG-DEVICE COMBINATION FOR CONTROLLING THE CONTRACTILITY OF MUSCLESxe2x80x9d to Ben Haim et al., incorporated herein by reference and PCT application PCT/IL97/00233 (International Publication Number WO 98/10830) titled xe2x80x9cFENCING OF CARDIAC MUSCLESxe2x80x9d to Ben Haim et al., incorporated herein by reference, PCT application PCT/IL97/00235 (International Publications Number WO 98/10831) to Ben Haim et al., titled xe2x80x9cCARDIAC OUTPUT CONTROLLERxe2x80x9d, incorporated herein by reference.
There also are known sensing electrodes such as the BIPOLAR SENSOR FOR MUSCLE TISSUE ACTION POTENTIAL DURATION ESTIMATION (Mika et al.) disclosed in U.S. patent application Ser. No. 09/280,486, filed Mar. 30, 1999, incorporated herein by reference.
Other catheters such as drug administration catheters, feeding catheters etc also exist.
The above mentioned devices, as well as other electro-cardiac devices employ electrode leads to transfer the electric signal from the electric device to the muscle tissue (in the case of signal providing devices, such as ETC in its active modality, pacemaker etc.) and/or in the opposite direction (such as the ETC in its passive modality, the action potential duration estimation sensor etc.)
Inserting the electrode leads into the desired location is quite an intricate task and a skilful hand is needed to guide the lead through the blood vessels, and especially through the coronary venous system of the patient, to the final destination in the heart. The complexity of this procedure lies in the problem of navigating the lead safely to its desired target position, passing through vascular junctions and bends, successfully using the right exits en route, and entering the desired path.
The problem arises from the physical and mechanical characteristics of the pacing lead: an electrode lead comprises an elongated body with one or more electrodes exposed at the lead""s distal end, electrically connected via electric wiring to a connector at the lead""s proximal end (designated to be connected to the pacemaker, ETC device or the like). The body of the lead is tubular, and is relatively soft, collapsible, and flexible, to increase its fatigue resistance and durability.
A common method of catheterization of a pacing lead in position inside the heart""s atrium or ventricle is to use a stiffening stylet, inserted inside and threaded through a lumen passing through the lead. When fully inserted through the lead, and advanced forward by pushing its proximal end, the distal tip of the stylet presses against the distal end of the lead, thus the pushing force at the proximal end of the stylet is transferred to the distal end of the lead, pulling the rest of the lead, trailed behind, through the desired route and into the atrium. For the lead to reach the ventricle, it is further passed through the valve separating the atrium from the ventricle.
Navigation of the lead is generally monitored using simultaneous xe2x80x9con-linexe2x80x9d fluoroscopic imaging, allowing the medical staff performing the catheterization to observe the advancement of the catheter to the desired location.
But if navigating the lead to the atrium or ventricle is an intricate task, navigating a lead into position inside the coronary veins is an even more a complex job. This is due to the fact that while the lead follows a path into the heart""s atrium that is relatively a straight one, with no substantial bends en route, in order to position the distal end of the lead inside the coronary veins, it must pass the coronary sinus and follow a multiple of bends along the way. In this case, the use of a stiffening stylet would prove problematic, as it is not suitable for maneuvering the lead around bends, and may also inflict damage to the blood vessel walls.
Several methods for the positioning of electrode leads inside coronary veins were developed and described in the art.
A known method of catheterization introducing a CS (coronary sinus) lead uses a lead pre-shaped to present a bent tip at its distal end, and incorporated with the use of a stiffening stylet. The bent-tip shape allows navigation of the stylet-driven lead around bends and junctions as the surgeon or technician advances the stylet and rotates the stylet to point the bent tip of the lead in the direction of the bend or desired exit. The pushing force applied on the proximal end of the stylet is transferred to the lead""s distal end along the stylet body. When the distal end of the lead reaches the atrium, its bent tip is designed to be easily maneuvered into the coronary sinus. Once the lead tip is inside the coronary sinus further pushing of the stylet advances the lead within the coronary sinus to its end, and into the great cardiac vein. See U.S. Pat. No. 5,683,445 (Swoyer), titled MEDICAL ELECTRICAL LEAD, filed Apr. 29, 1996.
Another known method of catheterization is referred to as over-the-wire catheterization. Mainly used in conjunction with mapping catheters, a guide-wire comprises a stiff but relatively flexible axially, long, thin wire. The guide-wire is pushed forward through the vein until the distal tip reaches a junction. The operator of the guide-wire jiggles with it until the tip enters the desired branch, and then resumes pushing the guide-wire forward. Once the guide-wire has reached the desired location, a catheter or a soft lead is threaded over the guide-wire and advanced to its designated location, and then the guide-wire is removed. An example for the over-the-wire guidance method is described in U.S. Pat. No. 5,389,087 (Miraki), titled FULLY EXCHANGEABLE OVER-THE-WIRE CATHETER WITH RIP SEAM AND GATED SIDE PORT, filed Jun. 29, 1992.
Mapping catheters, such as these used in electro-physiology laboratories (see for example U.S. Pat. No. 5,711,298, titled HIGH RESOLUTION INTRAVASCULAR SIGNAL DETECTION to Littmann et al.), have a semi-stiff lead body and thus the pushing force exerted on the proximal end is transmitted along the catheter""s body to its distal tip. The tip itself is more flexible than the rest of the body, and the catheterzation method is carried out in a similar manner to the insertion of the guide-wire described herein. The flexible property of the tip and the relative rigidity of the rest of the catheter body are crucial to the successful deployment of the catheter in this method.
Yet another method of catheterization relates to the monorail design of a mapping catheter. Here too a guide-wire is inserted first and positioned in place, and is used to navigate the catheter to its desired location. However, in this method, the catheter is provided with a perforation at its distal end. The perforated distal end of the catheter is threaded over the guide-wire, and pushed forward. As the catheter is advanced the guide-wire determines the direction of motion, and guides the catheter, its body passing along side the guide-wire, to its targeted position. Obviously, the catheter needs to possess some stiffness in order to be able to transfer the pushing force exerted on its proximal end along its body to the distal end.
An advantage of the monorail introduction method is the possibility of deploying lumen-free catheters, which therefore may be constructed to have smaller diameter, a feature that governs the extent to which a catheter can be inserted in vary narrow passages, such as the coronary venules.
Another advantage of the monorail introduction method is the abolishment of the need for a lengthy residual guide-wire outside the body of the patient, which in the case of the over-the-wire method has to be at least as long as the overall length of the catheter. In the monorail guiding and positioning method of deployment only a short portion of the guide-wire needs to protrude from the patient""s body, and as a result it minimizes the risk of the catheter dropping on the floor during handling by the medical staff while attempting to mount it over the guide-wire prior to its insertion into the patient""s body. The monorail method of catheterization requires the use of a relatively stiff catheter body, in order to enable the transfer of force from the proximal end to the distal end of the catheter and advance it to its target position.
Another method of guiding and positioning elongated flexible elements into place within a tortuous body passage was disclosed in U.S. Pat. No. 4,824,435, titled INSTRUMENT GUIDANCE SYSTEM (Giesy et al.), filed May 18, 1987, incorporated herein by reference. The guided elements, provided with annular guides adjacent their distal ends, are slid over a guide-wire extending through the passage. In order to provide column strength to advance the elements a tubular pusher was introduced, slidably received on the guide-wire.
Still another catheterization method is described in U.S. patent application Ser. No. 09/317,589, titled A DEVICE AND METHOD FOR DRAGGING AND POSITIONING OF A MEMBER WITHIN A DUCT IN A BODY (Malonek et al.), filed May 24, 1999, incorporated herein by reference. This method employs pulling mechanism instead of pushing mechanism (as described by Giesy et al.). The later method is suitable in particular (but not solely) for rapid exchange catheterization, where it is an advantage to keep the catheter hooked to the guiding device throughout the operation and leading to its removal.
The last two described method involve an additional guidance tool which pushes or drags the catheter to position. The catheter itself is engaged to the guide-wire at its distal end similarly to the monorail-type catheters, and therefore these introduction methods have similar advantages as the monorail method.
An important advantage of the last two methods is that they facilitates the introduction of soft bodied catheters, possessing no or little stiffness, as the catheter is guided in by applying pushing or pulling force on its distal end.
The present invention seeks to provide a catheter adapted for deployment using the monorail guidance and positioning method.
Furthermore an object of the present invention is to provide such catheter design that minimizes the risk of an abrupt inadvertent tearing of the catheter distal tip engaged to the guidewire, and consequent disengagement of the catheter from the guide-wire.
It is therefore provided, in accordance with a preferred embodiment of the present invention, a catheter, said catheter comprising an elongated body, having a proximal end and a distal end, wherein at the distal end of said catheter a cap is provided, attached to said distal end, said cap provided with passage adapted to receive a guide-wire slidingly passing through it.
Furthermore, in accordance with a preferred embodiment of the present invention, the catheter is an electrode lead.
Furthermore, in accordance with a preferred embodiment of the present invention, said cap is hollow and is provided with two aligned bores positioned on the cap""s mantle.
Furthermore, in accordance with a preferred embodiment of the present invention, said cap serves as an electrode.
Furthermore, in accordance with a preferred embodiment of the present invention, said passage internal diameter is in the range of 11 to 30 milli-inch.
Furthermore, in accordance with a preferred embodiment of the present invention, said passage is aligned diagonally with respect to the central longitudinal imaginary axis of the catheter.
Furthermore, in accordance with a preferred embodiment of the present invention, the angle defined between said passage and the catheter""s imaginary central longitudinal axis is not more than 45xc2x0.
Furthermore, in accordance with a preferred embodiment of the present invention, said angle ranges between 5xc2x0-20xc2x0.
Furthermore, in accordance with a preferred embodiment of the present invention, it is provided a catheter having a distal and proximal ends, wherein said catheter is provided with a cap at its distal end, said cap provided with a loop attached to it adapted to receive a guide-wire to pass through said loop.
Furthermore, in accordance with a preferred embodiment of the present invention, said loop is a looped wire.
Furthermore, in accordance with a preferred embodiment of the present invention, said loop is a tubular member.
Furthermore, in accordance with a preferred embodiment of the present invention, said cap is hollow, having a bore at its distal tip through which a looped wire is threaded, and wherein the looped wire is prevented from disengaging from the cap by means of a little disc, located at the inside of said cap, that is larger in size than the bore, and to which the looped wire is attached to.
Furthermore, in accordance with a preferred embodiment of the present invention, said disc is provided with a duct to allow fluids contained thin the catheter to pass through it and be discharged through bore.
Furthermore, in accordance with a preferred embodiment of the resent invention, said loop inner circumference ranges from 11 to 30 milli-inch.
Furthermore, in accordance with a preferred embodiment of the present invention, it is provided a catheter having a distal and proximal ends, wherein said catheter is provided with external coating, said coating at the distal end of the catheter, provided with a cleavage and a perforation substantially opposite the cleavage so as to allow a guide-wire to be passed through the cleavage and be threaded through said perforation.
Furthermore, in accordance with a preferred embodiment of the present invention, said catheter is an electrode lead.
Finally, in accordance with a preferred embodiment of the present invention, said external coating is made of bio-compatible electrically insulating material.